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ARM: 6384/1: Remove the domain switching on ARMv6k/v7 CPUs

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This patch removes the domain switching functionality via the set_fs and
__switch_to functions on cores that have a TLS register.

Currently, the ioremap and vmalloc areas share the same level 1 page
tables and therefore have the same domain (DOMAIN_KERNEL). When the
kernel domain is modified from Client to Manager (via the __set_fs or in
the __switch_to function), the XN (eXecute Never) bit is overridden and
newer CPUs can speculatively prefetch the ioremap'ed memory.

Linux performs the kernel domain switching to allow user-specific
functions (copy_to/from_user, get/put_user etc.) to access kernel
memory. In order for these functions to work with the kernel domain set
to Client, the patch modifies the LDRT/STRT and related instructions to
the LDR/STR ones.

The user pages access rights are also modified for kernel read-only
access rather than read/write so that the copy-on-write mechanism still
works. CPU_USE_DOMAINS gets disabled only if the hardware has a TLS register
(CPU_32v6K is defined) since writing the TLS value to the high vectors page
isn't possible.

The user addresses passed to the kernel are checked by the access_ok()
function so that they do not point to the kernel space.

Tested-by: Anton Vorontsov <cbouatmailru@gmail.com>
Cc: Tony Lindgren <tony@atomide.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
Catalin Marinas
2010-09-13 16:03:21 +01:00
committed by Russell King
parent ff8b16d7e1
commit 247055aa21
15 changed files with 153 additions and 92 deletions
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16
arch/arm/include/asm/uaccess.h
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@@ -227,7 +227,7 @@ do { \
#define __get_user_asm_byte(x,addr,err) \
__asm__ __volatile__( \
"1: ldrbt %1,[%2]\n" \
"1: " T(ldrb) " %1,[%2],#0\n" \
"2:\n" \
" .pushsection .fixup,\"ax\"\n" \
" .align 2\n" \
@@ -263,7 +263,7 @@ do { \
#define __get_user_asm_word(x,addr,err) \
__asm__ __volatile__( \
"1: ldrt %1,[%2]\n" \
"1: " T(ldr) " %1,[%2],#0\n" \
"2:\n" \
" .pushsection .fixup,\"ax\"\n" \
" .align 2\n" \
@@ -308,7 +308,7 @@ do { \
#define __put_user_asm_byte(x,__pu_addr,err) \
__asm__ __volatile__( \
"1: strbt %1,[%2]\n" \
"1: " T(strb) " %1,[%2],#0\n" \
"2:\n" \
" .pushsection .fixup,\"ax\"\n" \
" .align 2\n" \
@@ -341,7 +341,7 @@ do { \
#define __put_user_asm_word(x,__pu_addr,err) \
__asm__ __volatile__( \
"1: strt %1,[%2]\n" \
"1: " T(str) " %1,[%2],#0\n" \
"2:\n" \
" .pushsection .fixup,\"ax\"\n" \
" .align 2\n" \
@@ -366,10 +366,10 @@ do { \
#define __put_user_asm_dword(x,__pu_addr,err) \
__asm__ __volatile__( \
ARM( "1: strt " __reg_oper1 ", [%1], #4\n" ) \
ARM( "2: strt " __reg_oper0 ", [%1]\n" ) \
THUMB( "1: strt " __reg_oper1 ", [%1]\n" ) \
THUMB( "2: strt " __reg_oper0 ", [%1, #4]\n" ) \
ARM( "1: " T(str) " " __reg_oper1 ", [%1], #4\n" ) \
ARM( "2: " T(str) " " __reg_oper0 ", [%1]\n" ) \
THUMB( "1: " T(str) " " __reg_oper1 ", [%1]\n" ) \
THUMB( "2: " T(str) " " __reg_oper0 ", [%1, #4]\n" ) \
"3:\n" \
" .pushsection .fixup,\"ax\"\n" \
" .align 2\n" \